The present invention relates to a fluorescent lamp and a fluorescent lamp apparatus.
With regard to a conventional bulb-shaped fluorescent lamp or a compact fluorescent lamp or the like, structures like those disclosed, for example, in JP58(1983)-21379B, JP6(1992)-30221B and so forth are known. In these structures, a small-dimensioned arc tube formed by bending a glass tube once or twice into a U-shape or interconnecting glass tubes by a bridge is used. The arc tube is supported by a holder made of a heat-resistant resin and is combined with a case having a base and housing a lighting circuit, and furthermore, a glass globe or a resin globe is mounted over the arc tube. As the heat-resistant resin forming the holder, for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate (PC) or the like are used.
A fluorescent lamp without a globe is incorporated into an enclosed lighting fixture or a partially open type lighting fixture for use. Also a fluorescent lamp with a globe is often used in combination with the above-mentioned lighting fixtures.
In the conventional fluorescent lamp mentioned above, there was a problem that fogging occurred on the inner surface of the globe or the lighting fixture before the end of its lifetime, thereby causing reduction of emission beams and deterioration of luminous maintenance characteristics. In particular, such a problem became apparent for a fluorescent lamp with a high tube wall load.
As a result of investigating the cause for this problem, it became clear that the holder made of resin supporting the arc tube was vaporized and scattered partially by the effect of heat and a trace of ultraviolet rays emitted from the arc tube, which adhered to the inner surface of the globe or the lighting fixture in a form of smoke.
It is an object of this invention to solve the problem of the conventional fluorescent lamp, and to prevent the reduction of beams and improve the luminous maintenance factor.
A fluorescent lamp of the present invention includes an arc tube made of glass, a holder made of a heat-resistant resin for supporting the arc tube, and a case having a base combined with the holder. The glass of the arc tube has light transmittance with characteristics of 70% or less with respect to a wavelength of 340 nm, 50% or less with respect to 330 nm, and 15% or less with respect to 310 nm.
According to the glass of the arc tube, the transmittance of ultraviolet rays emitted from the arc tube is suppressed in a wavelength region of 310 nm to 350 nm. Therefore, even if the compact high output arc tube partially has a high tube wall temperature during lighting, the decomposition and the scatter of the resin components of the holder can be suppressed, and thus, the effect of preventing the reduction of emission beams or the deterioration of the luminous maintenance factor can be obtained.
In the above-mentioned configuration, it can be configured such that the arc tube has a structure in which a discharge path is formed by interconnecting a plurality of glass tubes.
Furthermore, in the above-mentioned configuration, it can be configured such that the arc tube at least partially has a tube wall temperature of 80xc2x0 C. or more during lighting, and that the arc tube is covered with a globe made of glass or resin.
A fluorescent lamp apparatus of the present invention contains any one of the fluorescent lamps of the configuration mentioned above in an enclosed appliance.
Furthermore, another configuration of a fluorescent lamp apparatus of the present invention contains any one of the fluorescent lamps of the configuration mentioned above in a partially open type lighting fixture.